Shock absorber for the elements of thermionic tubes



Feb. 22, 1938. w, KRAHL 2,108,987

SHOCK ABSORBER FOR THE ELEMENTS OF THERMIONIC TUBES Filed Feb. 13, 1933 INVENTOR WALTER Lou/s KRAHL BY fl MCJZ- L 22m;

ATTORNEY S Patented Feb. 22, 1938 UNITED STATES PATENT OFFICE SHOCK ABSORBER FOR THE ELEMENTS OF THERMIONIC TUBES Walter Louis Krahl, Montclair, N. J., assignor, by mesne assignments, to Arcturus Development Company, Newark, N. J a corporation of Delaware Application February 13, i933, Serial No. 656,490

' 2'! Claims.

This invention relates to thermionic devices and especially to a means for supporting an element assembly in such devices.

At the present time it is customary to provide certain types of thermionic devices such as electronic valves with additional elements besides the ordinary anode, control grid and cathode. Thus in some tubes various elements are added in the form of shield and other grids, shielding structures and barriers to minimize secondary emission, all of which tend to increase the weight of the entire electrode structure making it diflicult to mount the assembled elements upon the press of the tube as has heretofore been the custom. According to methods now in use, pointed finger supports are attached to theelement assembly which contact with the bulb wall, but considerable difliculty arises from the variation in commercial production of the desired diameter of the bulb at the point of support contact.

It is one of the objects of the invention to provide a means for supporting the upper end of an electrode or element assembly against transverse movement.

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Another object of the invention is to provide a resilient means for cushioning movement of the upper'end of an assembly of elements so as to absorb any shock caused by vibration 'or jar and prevent chattering of the elements.

Another object of the invention is to provide a resilient support for the upper end of an element assembly which is'adapted to engage the walls of the envelope but which will not interfere with the insertion of the elements into the envelope.

Another object of the invention is to provide a resilient engaging means for the wall of an envelope to support the upper end of an element assembly thereagainst which will prevent too rapid heat transfer to the envelope. thereby preventing the overheating thereof when the elements are raised to a relatively high temperature.

Other objects of the invention and objects relating particularly to the construction and as- V sembly of the various parts will be appreciated as the description proceeds.

One embodiment of the invention has been 11- lustrated in the accompanying drawingin which: Fig. 1 is a sectional plan viewof a thermionic multi-element tube embodying the invention taken on the line l--I of Fig. 2;

Fig. 2 is a front sectional elevational view the thermionic device shown in Fig. 1;

.sulated from the metal tube 3! Fig. 3 is a side sectional elevational view of the I tube shown in Fig. 2'; and

Fig. 4 is a perspective view of the shock absorbing element.

Referring now particularly to the drawing, the invention is shown in connection with a multieiement thermionic tube having an envelope l0 whose tapered lower end II is fused to a stem tube l2 which stands up inside of the envelope,

. terminating in a press ii for supporting the elements and through which the various lead-in wires pass. The upper end of the envelope ill, instead of the usual spherical top, is provided with a dome-shaped portion i4 and a cylindrical portion i5 between the dome-shaped portion and the main part of the envelope.

A pair of support rods iii are sealed, one. in each outer end of the press, and support a cylindrical anode l1. Inside of the anode I! are two parallel rods or standards I8 which are welded at their lower ends to two short support rods l9 which are sealed in the press IS. A disc is mounted between the two rods l8 at their lower ends thereof and has a central opening 2! provided with a downturned flange 22, this opening and flange extending completely across the disc so as to provide access for the support rods of other elements which come between these rods IS. The disc 20 is provided with an upturned flange 23 around the periphery thereof so as to hold a mica disc 24 as indicated in Fig. 3.

In like manner a similar disc 25 is mounted between the upper ends of the support rods i8. This disc has a longitudinal opening 26 extend ing across the disc and provided with an upturned flange 21, while its outer periphery is provided with a downwardly and inwardly turned flange for holding in place a disc 29 of mica which is thus held securely against the disc 25. The opening 2| in the disc 20 is aligned with the opening 26 in the disc 25.

The two mica discs 24 and 29 have holes 30 in the center thereof to receive and support the cathode 3| which is inthis case formed of a metal cylinder, as, for instance, nickel, within which is mounted a hairpin filament 32 connected at its lower end to two short support rods 33 sealed in the press IS. The filament 32 is, of course, in-

in any suitable or desirable manner.

Around the cathode 3| is provided a helical grid 34 which is wound upon two parallel support rods which extend through holes 36 in the mica discs so as to support the grid with respect to the cathode. One of the rods 35 is extended upwardly a short distance beyond the disc and to this red is connected a pliable wire 9'! which,

passes out through a tube 98 at the top of the envelope which is fused against the wire, and the wire is attached to a cap 39 cemented in place on the top of the envelope.

Around the control grid 34 is positioned another grid 4|, wound around two parallel support 4 lower end of one of the rods 46 is extended and welded to a rod 49 sealed in the press i9.

7 The two support rods [8 are extended somewhat beyond the top of the grid supporting rods and the cathode, and a dish-shaped member 49 is positioned over them above the other elements. This member 49 may be of nickel or other suitable metal and is provided with a flat circular portion 50 having sections of an annular rib embossed on the underside thereof which is large enough in diameter to just flt around the disc 25 when the member 49 is placed upon the disc. The flat portion 50 also has a longitudinal groove 52 through which the flange 21, attached to the disc 25, fits when the member 49 is placed in position. The two support rods I! extend upwardly through the groove 52 as indicated in Figs. 1 and 2.

The member 49 is provided with a flange 53 which extends upwardly all around the periphery of the member to a point about even with the top of the support rods l8, forming a cylinder whose diameter is somewhat less than the diameter of the cylindrical portion i5 of the envelope so that it is spaced from the envelope on all sides. The central portion 50 of the member 49 is preferably welded to the disc 25 upon which it rests and thus holds the upper end of the cathode and grid support rods which are spaced by the mica disc 29.

By holding the member 49, therefore, in position with respect to the envelope, the upper ends'of the cathode and grid support rods are also held.

The shock absorbing element of the invention is intended to space the member 49 from the-envelope in such a manner that shocks given the envelope are absorbed before they reach the element structure. To this end a rectangular piece of mica 54 (Fig. 4) preferably in elongated strip form having a back edge 56 and end edges 99, is provided with a pair of spaced slots 55 extendin from one side to a point about two-thirds across the member, the slots being parallel and arranged at right angles to the edge in which they are cut.

The corners of the edge 99 opposite from the slots are rounded as at 51 to effect. easy assembly as will be apparent hereafter. The slots 59 form a tongue 99 between them andtwo end tongues 59 as will be clearly, evident from an inspection of the figure.

In the device illustrated.,I have shown two of -the-mica shock absorbers, one on. each side of the member 49. and positioned upon'the flange 53 with the tongue 99 of each on the inside of the'flange and the tongues 99 of each on the outside, the .ilange passing through the slots 59. Thus p'osihoned the tongues 99 protrude outwardly, as clearly indicated in Fig. l, and the edges thereof contact with the cylindrical portion I! of the envelope. The mica shock absorbers are so designed that they are too long to fit into the cy namass? drical portion 'l! of the bulb without bending, and

hence when the elements are inserted into theenvelope the two mica members 54 first strike the wall of the envelope l9 before they reach the cyeach of the mica members bending slightly as this is done, so that finally the edges of the tongues 59 press firmly against the wall of the envelope but with the whole mica element under slight tension. The member 49 is thus held firmly but resiliently within the cylindrical portion ii of the envelope andaccordingly holds the upper end of the element structure against transverse movement, at .the some time absorbing shocks and preventing chattering.

It will be noted that the mica element 54 is made long enough so that displaced sections of its edges contact under tension with curved sections of the tube wall whereby the plate bends throughout its entire length in a slight arc as indicated in Fig. 1. Furthermore, because of the flexibility of the mica tongues 59 and 59 the ele- P limited pivotal movement on the edge of the flange 53, which, in conjunction with the lengths wise flexibility of the spacing element, permits considerable tolerance in the diameter of the envelope. An envelope having a smaller diameter will cause the shock absorber to bend more than is indicated in Fig. 1 while a larger diameter will cause less bending, but in either case the ment-- ber 49 will be securely positioned, This fact is especially desirable due to theiact that the envelopes cannot be obtained all exactly the same size, the diameter often differing a small fraction of an inch.

While .two shock absorbers have been illustrated in the drawing, it is evident that more than two can be used with equally good results although I have found two sufficient for the purpose.

The shock absorbing elements are easily slipped onto the member 49 and then the whole element structure may be easily inserted in the envelope by gently pushing with the shock absorbers automatically centering the elements. This last funct on is also an important improvement as it eliminates the step of straightening the elements within the envelope after the envelope has been fused to the stem tube as is often necessary in tubes with the elements supported merely upon the press.

Inasmuch as the mica shock absorbers do not conduct heat readily, the contacting points on the envelope are kept cool so that it cannot be-- come overheated due to the flow of heat from the elements to the glass. Other materials besides mica may be used, however, although I prefer to use a material having a low heat conduc- I and facilitates the mounting of the element ment 54 yields bodily along itswidth with a structure within envelopes which may vary conslderably in size. when in use it not only helps to support the element structure within the en'- veiope but acts as a shock absorber preventing damaging shocks from affecting the elements.

Many modifications of the invention may be resorted to without departing from the spirit thereof, and I do not therefore desire to limit myself to what has been shown and described except as such limitations occur in the appended claims.

What I claim and desire to secure by Letters Patent is:

1. A thermionic device comprising an envelope, a press within said envelope and integral therewith, a support member within said envelope and having its lower end mounted upon said press, a plurality of adjustable mica elements, and means'to detachably secure said elements upon the upper end of said support member with said elements protruding outwardly so that their ends contact with the inner walls of said envelope, said elements lying inplanes substantially Dara]- lel to the axis of the support member.

2. A thermionic device comprising an envelope, a press within said envelope and formed integral therewith, a standard within said envelope and having its lower end connected to said press, a tubular member mounted on the upper end of said standard, a resilient plate having a pair of slots therein, said plate being positioned upon said tubular member so that said tubular member passes through said slots, said Plate being long enough to contact with the walls of said envelope thereby placing the plate under slight tension.

3. A thermionic device comprising an envelope, a press within said envelope, a standard within said envelope and having its lower end mounted on said press, a cylindrical member mounted upon the upper end of said standard. and a plurality of mica plates positioned substantially tangentially to said cylindrical member, said plates having a pair of slots in each forming a tongue which fits over the edge of said cylindrical member, thereby holding said mica plates in position by their own resiliency, said plates being long enough to contact with the inner wall of said envelope and maintain said cylindrical member in position therein.

4. A thermionic device comprising an envelope having a rounded portion and an upper tubular portion, a press within said envelope and integral with the lower end thereof, an electrode assembly within said envelope, means to mount the lower end of said electrode assembly upon said press, a tubular member attached to the upper end of said electrode assembly and lying within said tubular portion of the envelope, and a plurality of mica plates secured to said tubular member and resiliently engaging the inner wall of said tubular portion of said envelope.

5. A thermionic device comprising an envelope having a rounded portion and an upper cylindrical portion, a press within said envelope and formed integral with the lower end thereof, an electrode assembly within said envelope, means to mount said electrode assembly upon said press, a cylindrical member attached to the upper end of said assembly and a plurality of mica plates having resilient tongues'to fit over the edge of saidcylindrical member and having ends extending outwardly and contacting with the inner wall of the cylindrical portion of said envelope to hold said electrode assembly in position, said mica plates being held in position upon said cylindrical member by their own resiliency.

6. A shock absorber for the electrode element within a thermionic tube comprising a plate of resilient material having a plurality of parallel slots extending partially across said plate from one edge thereof forming tongues adapted to engage said element. 7

7. A shock absorber for the elements of a thermionic device comprising a mica plate having a pair ofslots extending partially across said plate from one edge thereof. W

8. A shock absorber for the elements of a thermionic device comprising a substantially rectanmionic devicev comprising an approximately rectangular mica plate having a pair of slots ex-' tending partially across said plate from one edge thereof and having the corners of the opposite edge rounded.

10. A device of the class described comprising a tube, a support therein, an electronic valve assembly unit mounted on said support, and means for resisting lateral movement of said unit, said means consisting of a separable resilient element loosely connected to said unit. 5

11. A device of the class described comprising a tube, a support therein, an electronic valve assembly unit mounted on said support, and means for resisting lateral movement of said unit, said means comprising plural resilient elongated spacer elements, both ends only of each of said elements contacting freely and yieldingly against the tube wall and the body of each element intermediate its ends being attached'yieldingly to the valve unit.

12. A device of the class described comprising a tube, a support therein, an electronic valve assembly unit mounted on said support, and means for resisting lateral movement of said unit, said means comprising two diametrically positioned shock absorber plates each loosely and separably attached to the valve 'unit and each contacting with the tube wall at an angle to the diametric line joining the points of the tube contact and the tube axis.

13. A device of the class described comprising a tube, a support therein, an electronic valve assembly unit mounted on said support, and means for resisting lateral movement of said unit, said means comprising a flexible spacer element hav-,

a tube, a support therein, an electronic valve unit mounted on said support, said unit including valve parts and a normally inflexible spacing member therefor, and means consisting of a separable, flexible element loosely connected to said member for spacing the unit from the tube.

15. A device of the class described comprising a tube, a support therein, an electronic valve unit mounted on said support, said unit including valve parts and a normally inflexible spacing member therefor, and a separable resilient element attached loosely to said member only and contacting with said tube.

16. A device of theclass described comprising a tube, a support therein, an electronic valve unit mounted on said support, said unit including valve parts and a normally inflexible spacing member therefor, and a plurality of flexible flat strips interposed between said member and tube,

each strip being loosely attached to the member -rocking movement thereon and engaging the wall of said tube.

18. A device of the class described comprising a tube, a support therein, an.- electronic valve unit mounted on said support, said unit including valve parts'and a flat and normally inflexible spacing member therefor positioned approximately at right angles to the axis of the unit, and a separable flexible element secured to said member, the flexing of said element occurring toward the axis of the tube.

19.. A device. of the class. described comprising a tube. a support therein, an electronic valve unit mounted on said support, a spacing and retaining member therefor, and means for resisting lateral movement of said unit, said means comprising a flat resilient strip freely contacting at 80 its ends against the wall of the tube and attached to said member, said strip lying in a. plane approximately parallel to the axis of the tube.

20. A device of the class described including a tube, a support therein, an electronic valve unit mounted on the support, said unit including valve parts and an upperholding plate' for the parts positioned at right angles to the tube axis, and an elongated strip of insulating material attached to the plate intermediate its ends,

the ends of the strip contacting freely on the tube wall at points adjacent the intersection with said tube wall of a plane including the" upper plate. v 4 I 21. A device of the class described including a tube, a support therein, an electronic valve unit mounted on the/support, said unit including valve parts and an upper holding plate for the parts positioned at right angles to the tube axis, and an elongated strip of mica attached to the plate intermediate its ends and the ends 01 the strip contacting freely under tension against the tube wall whereby the strip assumes a curved form, the curvature of the strip being less than that of the tube wall.

22. A deviceof the class described comprising a tube, a support therein, an electronic 'valve assembly unit mounted on said support, and

means for resisting lateral movement of said unit, said means comprising a plate resilient throughout its area attached, to said unit, the pins of said plate being parallel to the unit axis and having displaced sections of the edgesthereof contacting-under tension with curved sections of the tube wall whereby the plate between the edges is deformed.

23. A thermionic tube comprising an envelope, a. press within the envelope and formed integral therewith, a cup-shaped support member mounted on said press, the base of said cup lying in a plane approximately at right angles to the axis of the tube, a removable resilient member mounted on the side wall of said cup so as to lie in a plane approximately parallel to the axis of the tube, said resilient member at its end edges contacting with said tube at points of the tube approximately in the'plane of the base of the cup, said resilient member being under slight tension due to the opposite compression of the sides of the wall of the cup member and the tube.-

24. A device of the,class described comprising an envelope, a base member within said envelope, operating elements mounted on said base,

a flat support member having an axially extend- 7 ing flange wall thereon mounted in connection with said element and adjacent the wall of said envelope, a resilient plate having three tongues extending from one edge thereof, the middle tongue extending over the interior side of the flange wall of said support member, and the two outer tongues extending on the outside of the flange wall of said member, whereby the resilient member is yieldingly held to the support member, the outer edges of said outside positioned tongues contacting with the wall of the envelope at points adjacent to the transverse portion of said support member. I

25. An electron discharge device comprising an envelope with a tubular portion, a mount enclosed by said envelope and comprising an electrode assembly, supporting means attached to said mount and extending within said tubular portion, and springs oi insulating material engaged intermediate their ends by said supporting means and set perpendicularly'to a transverse axis of; said tubular portion with their ends in engagement with the walls of said tubular portion to resiliently support said mount within said envelope.

26. In combination, an envelope containing an electrode assembly, and separable means resiliently spacing said assembly from the wall of said envelope comprising a substantially E- shaped insulator. 

